#define _CRT_SECURE_NO_WARNINGS 1
class Solution {
public:
    int combinationSum4(vector<int>& nums, int target) {
        vector<double> dp(target + 1);
        dp[0] = 1;
        for (int i = 1; i <= target; i++)
            for (int j = 0; j < nums.size(); j++)
                if (i >= nums[j])
                    dp[i] += dp[i - nums[j]];
        return dp[target];
    }
};